feat: version fixes

[burnjake]

Current builds are pulling in go version 1.2 rather than 1.20 which may be causing the go dependency issues. These seem to be fixed after passing a string rather than a number as it stops the trailing 0 from being truncated.

After changing this, the kingpin module breaks with:

Error: ./main.go:75:16: cannot use kingpin.CommandLine (variable of type *"gopkg.in/alecthomas/kingpin.v2".Application) as *"github.com/alecthomas/kingpin/v2".Application value in argument to flag.AddFlags

Using the correct kingpin v2 module path fixes the typing.

It seems to start ok locally:

$ ./domain_exporter --config="domains.yaml"
ts=2023-08-17T12:15:18.186Z caller=main.go:82 level=info msg="Starting domain_exporter" version="(version=, branch=, revision=3c440d2ef68e3edd4ae164afbae70bbb1e55d87b)"
ts=2023-08-17T12:15:18.186Z caller=main.go:83 level=info msg="Build context" (gogo1.21.0,platformdarwin/arm64,user,date,tagsunknown)=(MISSING)
ts=2023-08-17T12:15:18.186Z caller=main.go:123 level=info msg=Listening port=:9203
ts=2023-08-17T12:15:18.250Z caller=main.go:176 level=info domain:=google.com date=2028-09-14T04:00:00Z
ts=2023-08-17T12:15:18.303Z caller=main.go:110 level=warn warn="Unable to parse date: Last updated:  10-Dec-2020, for bbc.co.uk\n"
ts=2023-08-17T12:15:18.335Z caller=main.go:176 level=info domain:=ycombinator.com date=2024-03-20T22:51:07Z```

CI passes on a PR on the fork: burnjake#1

[victorbiga]

@shift can you allow the GH to run and approve this PR if successful pls